Progress on whole atmosphere lidar John Smith Research Associate, CIRES April 28th, 2015 Working Group on Space-based Lidar Winds

Whole atmosphere lidar concept, Fe-Doppler system from Chu et al, Proc. of 24th ILRC, 2008

Measurement capability Temperature only Rayleigh technique Temperature and wind Fe Doppler technique Routine Sporadic Wind Rayleigh Doppler technique Future capability

Comparing Na and Fe Doppler lidars for whole atmosphere wind and temperature profiling Na Doppler (589 nm) Fe Doppler (372 nm) Typical transmitter power 0.5 W >4 W Terrestrial Rayleigh volume backscatter coefficient 1.19∙10-6 1/km/sr 7.90∙10-6 1/km/sr Max. output current for available high QE PMT 2 μA (GaAsP) 100 μA (UBA) Ratio of stimulated emission timescale to natural lifetime (τS/τN) 40 221 Optical pumping effects Yes No 8x 6x

Mach-Zehnder approach XMZ technique: Measurement is independent of source spectrum and instrument defects

Progress on instrumentation $30k budget

Instrument tests Source fiber core (filled) diameter 1000 μm, NA 0.22

Expected performance XMZ technique Fe Doppler technique

Fe Doppler status First light attained on Sept. 7, 2014 Wavelength stabilization accomplished using high precision wavemeter in the field Optical heterodyne detection of UV reference pulse obtained in the lab Wavelength stabilization to Fe fine structure achieved in the lab

Conclusions Fe is competitive with Na in wind and temperature of the mesopause region and far superior below the metal layer The Mach-Zehnder technique preserves all signal and allows profiling of wind at the same time as wind and temperature in the mesopause Ratios of colors/frequencies and channels can be solved for the Doppler shift independent of variations in backscatter spectrum and instrument defects Good fringe contrast has been demonstrated for a source representative of the real optical extent Progress is being made on the base Fe Doppler lidar, first measurements expected by July